Ocean Acidification Hits Northwest Oyster Farms

By DARCY BONFILS

April 22, 2010 

Mark Wiegardt and Sue Cudd have each dedicated about 30 years of their lives to bringing oysters to our tables. Now the two have found themselves in the forefront of one of the newest, most pressing environmental issues of our time: ocean acidification.

It all began with the oyster larvae at their Whiskey Creek Shellfish Hatchery in Tilamook, Ore.

"It first started in 2007. We had a situation here when all of a sudden, our larvae started dying," said Wiegardt.

"At first we started wondering, what is wrong? Bacterial problems? What are we doing wrong?" Cudd said.

Desperate, Wiegardt and Cudd turned to expert oceanographer Burke Hales and his team from Oregon State University to study the new and alarming enigma. They learned that the Pacific waters piped into their hatchery from nearby Netarts Bay were the cause of the dying larvae.

Dying Larvae Depleting Oysters and Other Shellfish

Whiskey Creek's 8,000 gallon water tanks take in water from the Pacific Ocean and Netarts Bay. The water used in the hatchery is rough-filtered and heated, and pumped into the tanks that house roughly 48 million swimming larvae. If the larvae stop swimming, that's a problem.

The scientists went to work and learned that something was making the oceans too acidic and preventing the oyster larvae from growing shells. No shells means certain death.

When winds blew the ocean's deep carbon-rich waters onto the surface, hatcheries up and down the Northwest Pacific Coast began to suffer the same fate as Whiskey Creek.

"The chemistry is very simple. It is 101. Carbon dioxide makes the water more acidic, that is irrefutable," said Burke Hales, Oregon State University professor of oceanography.

Oceans act as sponges. According to the Natural Resources Defense Council, the oceans soak up one-quarter to one-third of all CO2 from fossil fuels. About 500 billion tons have been absorbed by the seas. Close to 22 million tons of C02 a day mix with the natural carbon of the ocean. But too much carbon and water makes the ocean too acidic.

Plants need carbon to grow, and animals exhale it with every breath. But too much carbon creates a problem. Where will it be stored, and how will it affect the chemistry of the planet?

Carbon Dioxide -- CO2 -- a Mixed Blessing

"At first, scientists thought, Oh, isn't this great, the ocean's taking up carbon dioxide that's resulting in less greenhouse warming. And it's only later that scientists realize this carbon dioxide in the oceans forms carbonic acid, and that attacks the shells of marine organisms," said Ken Caldeira, a climate scientist at the Carnegie Institute at Stanford University.

According to the NRDC, ocean acidity has increased by 30 percent since the Industrial Revolution of the 18th and 19th centuries. Scientists have used mathematical models to demonstrate that if we continue to pollute, ocean acidity will double by the end of the century, compared with what it was in preindustrial times.

"While the effects are just beginning to be seen in our hatcheries, the oceans are now changing faster than they have ever changed over the last 200 million years," said Richard Freely of the National Oceanic and Atmospheric Administration, who has been studying ocean acidification for 20 years.

"The effects can be seen in the weaker shells of oysters, clams, mussels, lobsters and shrimp. Smaller-shelled creatures, such as those at the bottom of the food chain, which most fish eat, are also dwindling away," said Freely. "Corals have a hard time forming too." Ocean acidity, said Freely, threatens the entire $2 billion U.S. shellfish industry.

According to the United Nations Environmental Program, if carbon emissions continue on a path of business as usual, scientists predict vast areas of the Pacific, Arctic and Antarctic Oceans will become so corrosive that shellfish will dissolve, causing ripple effects throughout the food web.

"We're risking something that will really change the way the oceans are for the rest of human civilization," said Standord's Caldeira.